Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Make cluster replicas return ASK and TRYAGAIN #495

Merged
merged 3 commits into from
May 24, 2024
Merged

Make cluster replicas return ASK and TRYAGAIN #495

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
689ee06
Make replicas return ASK and TRYAGAIN
zuiderkwast May 13, 2024
7f8edc1
Merge branch 'unstable' into replica-return-ask-redirect
zuiderkwast May 23, 2024
b1461ee
Fix badly resolved merge conflict
zuiderkwast May 23, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
17 changes: 10 additions & 7 deletions src/cluster.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1080,12 +1080,14 @@ clusterNode *getNodeByQuery(client *c, struct serverCommand *cmd, robj **argv, i
* can safely serve the request, otherwise we return a TRYAGAIN
* error). To do so we set the importing/migrating state and
* increment a counter for every missing key. */
if (n == myself &&
getMigratingSlotDest(slot) != NULL)
{
migrating_slot = 1;
} else if (getImportingSlotSource(slot) != NULL) {
importing_slot = 1;
if (clusterNodeIsMaster(myself) || c->flags & CLIENT_READONLY) {
if (n == clusterNodeGetMaster(myself) &&
getMigratingSlotDest(slot) != NULL)
{
migrating_slot = 1;
} else if (getImportingSlotSource(slot) != NULL) {
importing_slot = 1;
}
}
} else {
/* If it is not the first key/channel, make sure it is exactly
Expand Down Expand Up @@ -1154,8 +1156,9 @@ clusterNode *getNodeByQuery(client *c, struct serverCommand *cmd, robj **argv, i
/* MIGRATE always works in the context of the local node if the slot
* is open (migrating or importing state). We need to be able to freely
* move keys among instances in this case. */
if ((migrating_slot || importing_slot) && cmd->proc == migrateCommand)
if ((migrating_slot || importing_slot) && cmd->proc == migrateCommand && clusterNodeIsMaster(myself)) {
return myself;
}

/* If we don't have all the keys and we are migrating the slot, send
* an ASK redirection or TRYAGAIN. */
Expand Down
48 changes: 46 additions & 2 deletions tests/unit/cluster/slot-migration.tcl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,7 @@ start_cluster 3 3 {tags {external:skip cluster} overrides {cluster-allow-replica
set R3_id [R 3 CLUSTER MYID]
set R4_id [R 4 CLUSTER MYID]
set R5_id [R 5 CLUSTER MYID]
R 0 SET "{aga}2" banana

test "Slot migration states are replicated" {
# Validate initial states
Expand Down Expand Up @@ -139,8 +140,51 @@ start_cluster 3 3 {tags {external:skip cluster} overrides {cluster-allow-replica
assert_equal [get_open_slots 3] "\[609->-$R1_id\]"
assert_equal [get_open_slots 4] "\[609-<-$R0_id\]"
catch {[R 3 get aga]} e
assert_equal {MOVED} [lindex [split $e] 0]
assert_equal {609} [lindex [split $e] 1]
set port0 [srv 0 port]
assert_equal "MOVED 609 127.0.0.1:$port0" $e
}

test "Replica of migrating node returns ASK redirect after READONLY" {
# Validate initial states
assert_equal [get_open_slots 0] "\[609->-$R1_id\]"
assert_equal [get_open_slots 1] "\[609-<-$R0_id\]"
assert_equal [get_open_slots 3] "\[609->-$R1_id\]"
assert_equal [get_open_slots 4] "\[609-<-$R0_id\]"
# Read missing key in readonly replica in migrating state.
assert_equal OK [R 3 READONLY]
set port1 [srv -1 port]
catch {[R 3 get aga]} e
assert_equal "ASK 609 127.0.0.1:$port1" $e
assert_equal OK [R 3 READWRITE]
}

test "Replica of migrating node returns TRYAGAIN after READONLY" {
# Validate initial states
assert_equal [get_open_slots 0] "\[609->-$R1_id\]"
assert_equal [get_open_slots 1] "\[609-<-$R0_id\]"
assert_equal [get_open_slots 3] "\[609->-$R1_id\]"
assert_equal [get_open_slots 4] "\[609-<-$R0_id\]"
# Read some existing and some missing keys in readonly replica in
# migrating state results in TRYAGAIN, just like its primary would do.
assert_equal OK [R 3 READONLY]
catch {[R 3 mget "{aga}1" "{aga}2"]} e
assert_match "TRYAGAIN *" $e
assert_equal OK [R 3 READWRITE]
}

test "Replica of importing node returns TRYAGAIN after READONLY and ASKING" {
# Validate initial states
assert_equal [get_open_slots 0] "\[609->-$R1_id\]"
assert_equal [get_open_slots 1] "\[609-<-$R0_id\]"
assert_equal [get_open_slots 3] "\[609->-$R1_id\]"
assert_equal [get_open_slots 4] "\[609-<-$R0_id\]"
# A client follows an ASK redirect to a primary, but wants to read from a replica.
# The replica returns TRYAGAIN just like a primary would do for two missing keys.
assert_equal OK [R 4 READONLY]
assert_equal OK [R 4 ASKING]
catch {R 4 MGET "{aga}1" "{aga}2"} e
assert_match "TRYAGAIN *" $e
assert_equal OK [R 4 READWRITE]
}

test "New replica inherits migrating slot" {
Expand Down
Loading